The present invention relates to an apparatus for forming an end portion of a pipe and, more particularly, to an apparatus for carrying out, at a working site, plastic formation of an end portion of a refrigerant pipe of a refrigerating machine in a simple manner and in such a way that the end portion of the pipe will assume a predetermined profile suitable for connecting two pipe ends through a pipe coupling.
It has been known that plastic formation is carried out at one or both ends of a refrigerant pipe at a working site so that one or both ends of the pipe have a suitably profiled sectional shape in order to facilitate the connection of two pipes through a pipe coupling by merely inserting the formed ends of the pipes into the pipe coupling with a single action. A known pipe-end forming apparatus generally comprises a pipe holding device for rotatably holding a pipe to be formed, a plurality of profile rolls arranged around the peripheral surface of the tip end portion of the pipe held by the pipe holding device so as to press against the pipe end portion during the rotation thereof, and hydraulic cylinders for thrusting the profile rolls radially inwardly against the pipe.
In the known apparatus of the type described above, the profile rolls are radially inwardly pressed by the hydraulic cylinders against the outer peripheral surface of the end portion of the pipe which is caused to rotate whereby a profile complementary to the profile of the profile rolls is formed on the pipe end portion by plastic deformation.
In the case of the known apparatus of the type described above, the forces produced by the hydraulic cylinders are exerted radially to urge the profile rolls to press against the end portion of a pipe, and therefore the hydraulic cylinders must be extended radially outwardly. As a result, the forming apparatus must necessarily be large in bulk. Furthermore, since a pipe to be formed normally having a relatively large length must be rotated so that the pipe holding device is necessarily complex in construction and large in size. Such forming apparatus large in size is very inconvenient for transportation to a working site at which pipes are processed.